<template>
  <div>
    <input type="text" v-model.number="currenAge">
    <input type="text" v-model="nextAge">
  </div>
</template>

<script>
export default {
  data() {
    return {
      currenAge:''
    }
  },
  computed: {
    nextAge: {
      get() {
      return this.currenAge + 1
    },
    set(newValue) {
      this.currenAge = newValue - 1
    }
   }
  }
}
</script>

<style>

</style>